In a typical video conferencing on an Internet Protocol (IP) network, an expensive multipoint control unit (MCU) receives media from a plurality of terminals at different locations, combines the media from the terminals, and transmits a combined media to the terminals.
According to the scheme, however, when it is desired to allow as many terminals as possible to access the MCU on a session, the MCU has a resource burden proportional to the number of the terminals to be connected and has to be equipped with communication sockets of which number increases as the number of the terminals. As a result, there exists a problem that the network bandwidth for transmitting the combined media to the connected terminals may be concentrated and uneven.
According to an approach to solve the above problem, MCUs are categorized into master units and slave units to allow lots of geographically distributed terminals to connect to the system on a single session. According to this method, however, the media combined by the slave MCU happen to be re-combined by the master MCU, which results in a lack of flexibility in an image layout processing and an additional expense burden for the MCUs.
According to another method, a relay server relays streaming of the media data for the video conferencing. However, the terminals connected through the relay server cannot participate in bidirectional communications but may receive only unidirectional services of receiving the relayed media data.
In other words, conventional group communication methods for the video conferencing, for example, has been forced to rely on the performance of the MCU and the network bandwidth in order to provide high-quality communications while maintaining a bi-directionality to the users communicating on the same session. Thus, according in the conventional methods, it was difficult to process large-scale video conferencing in which the image layout may be changed flexibly and all the session participants may access the system while maintaining the bi-directional communications state.
A group communication method disclosed in Korean Patent No. 10-1085063 entitled GROUP COMMUNICATION METHOD IN MEDIA SERVER SYSTEM WITH DISTRIBUTED STRUCTURE filed by the present applicant has some similarities with the present disclosure in that both disclosures utilize distributed architectures. FIG. 6 is a flowchart illustrating the group communication method disclosed in the above document.
According to the method of FIG. 6, since the media data and the control signal transferred between the terminals are simply relayed by the data transmission processing system having the distributed architecture, the amount of video or audio data that the terminals connected on a same session receives from another terminals through the data transmission system may increase inevitably as the number of the terminals providing the video or audio increases.
Due to such limitations, the terminals place a heavy burden of decoding the media data on the CPU. Even worse, the bandwidth of the receiving network may limit the number of terminals capable of providing the video or audio on the same session. As a consequence, it is difficult to apply the method to mobile devices such as smartphones commonly being used currently due to the limitation of the CPU.
Accordingly, there is a need for a new terminal connection processing method that is different from the conventional MCU-based method so as to provide services to a plurality of terminals including mobile devices while maintaining bi-directional communications on the same session and ensuring the layout flexibility.